In a camshaft free combustion engine a pressure fluid, such as a liquid or a gas, is used to achieve a displacement/opening of one or more engine valves. This means that the camshafts, and related equipment, that conventional combustion engines use to open engine valves to let air in respective let exhaust fumes out from the combustion chamber, has been replaced by a less volume demanding and more controllable system.
In an engine that is constructed for significant angular momentum outputs, the pressure in the combustion chamber is increasing proportional to an increased angular momentum output, and the force that is required to open the valve actuator to open the, in relation to the combustion chamber inward opening, engine valve consequently also increases proportional to an increased angular momentum output. At high numbers of revolutions, such as 6-8000 rpm, a very fast opening of the engine valve is also required for the filling of air respective evacuation of exhaust fumes from the engine cylinder not to be restricted. These requirements, i.e. the need for an extremely fast opening at high frequencies in a high performance engine having high counter pressure in the combustion chamber of the engine at the opening of the exhaust valves, require the pressure of the pressure fluid upstream of the valve actuator to be high, in the order of 8-30 bar.
Downstream the valve actuator, the pressure fluid has a lower pressure, in the order of 3-6 bar, and when the pressure of the pressure fluid shall be increased by way of a compressor from the low pressure downstream of the valve actuator to the high pressure upstream of the valve actuator, a temperature rise occurs that increases concurrently with an increased pressure condition.
The valve actuator employs both pneumatics and hydraulics for its operation, and in valve actuator solutions, the risk is great that gas and hydraulic fluid is mixed due to the sealing between the different fluids is not one-hundred-percent tight, and with time there is a risk that the fluids will influence each other negatively.
Further, it can be a problem that the hydraulic liquid pressure that is present in the conventional oil system of the engine is not always sufficient for the hydraulics in a valve actuator to function appropriately as the valve actuator generate rapid motions with a high frequency, and if the pressure of the pressure fluid is greater than the pressure of the hydraulic liquid, the pressure fluid will enter and mix with the hydraulic liquid.